Proton spin structure and quark-parton model

The alternative to the standard formulation of the quark-parton model is pr oposed. Our approach is based on the solution of the master equations relat ing the structure and distribution functions, which consistently takes into account the intrinsic quark motion - in contradistinction to the standard infinite momentum approach, in which this motion is latently suppressed. Th e model well reproduces the experimental data on the both polarized and unp olarized structure functions, assuming that only the valence quarks term co ntributes to the nucleon spin. It is shown, the combined analysis of the po larized and unpolarized data can give an information about the effective ma sses and intrinsic motion of the quarks inside the nucleon. Simultaneously, it is shown that the rate of the nucleon energy carried by the quarks can be less, than estimated from the standard approach. As an addition, a predi ction for the proton spin function g(2) is given.